The two PG&E studies show that electrodialysis
is the clear energy-efficiency
winner for the clarification process.
However, the studies also show that
makingmodest changes to the cold stabilization
process can significantly increase
efficiency for this commonly used
method.

Since insulation potentially
accounts for the majority of cold stabilization
energy savings, winemakers
are encouraged to insulate tanks. In
fact, according to a PG&E Non-
Residential New Construction study
prepared by Applied Technology
Services, simply installing three
inches of insulation around tanks can
cut energy use by almost 95%. This
supports the dramatic drop in electricity
— from 1,200 to 22 Wh per gallon
— between the two test sites in the
Emerging Technologies studies.

In addition to energy savings, electrodialysis
offers the benefits of less
processing time and reduced wine loss.
Although these benefits go beyond the
scope

Table III: Electrodialysis stabilization measurement points

Measured parameter

Logging method

Logging interval

Wine inlet temperature

data logger

15 min.

Wine outlet temperature

data logger

15 min.

Wine initial conductivity

winery personnel

Start

Wine final conductivity

winery personnel

End

Wine initial pH

winery personnel

Start

Wine final pH

winery personnel

End

Energy consumption of ED system

data logger

15 min.

Water consumption

winery personnel

1 per batch

ED pump on/off status

data logger

Varies

of the study, winemakers are
reminded to
take these into consideration
when weighing the pros and cons
of adopting electrodialysis technology.
Other considerations such as space,
time, and winemaking style must be
taken into account.

The nuances and long-term plans of
each winery will influence the most
appropriate method.Winemakers must
be especially aware that adopting electrodialysis
technology results in
increased water
consumption that
necessitates increased wastewater treatment
and associated costs.

Fetzer Vineyards was in a unique
position in that they already employed
multiple water conservation methods
and it was therefore
easy to accommodate
extra waste water. Winemakers
who do not have this capability must
be prepared for increased water related
expenses. To that end, PG&E
will conduct a study in which winery
wastewater treatment practices will be
examined and benchmarked.

"We are aware that electrodialysis
uses more water than traditional stabilization,"
says Fetzer's Thrupp.
"However, the relatively small
increase in water for this technology
is addressed and compensated for by
ongoing water conservation practices
throughout the winery, bottling facility,
and vineyards. In addition, the
water is treated on-site through aeration
ponds and is reused in the vineyards
and landscaping."

PG&E supports the adoption of electrodialysis
technology forwine stabilization
as an energy efficiency tool, and
encourages winemakers to insulate
tanks to save energy in the cold stabilization
process. To that end, PG&E is
currently offering incentives for adopting
non-mobile electrodialysis technology
or for insulating wine tanks.
To find out how PG&E can evaluate
your possible energy savings using
electrodialysis technologies, call the
PG&E Business Customer Service
Center (800/468-4743) and ask for the
project manager in your area.

[Steve Fok, PE, has been managing
power generation, environmental compliance,
and energy efficiency projects at
PG&E for 29 years. Steve can be reached at
415/223-4735 or SKF2@pge.com.]